1.4 cells and batteries - student version

8/11/2019 1.4 Cells and Batteries - Student Version

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Section1.3 - 1.4Electrical Safety

Cells and Batteries


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Background

Chemical reactions release free ______________

These free electrons must flow from the (-) terminal of a cell

to the (+) one to complete a circuit

An ____________ is a paste or liquid that conducts electricitybecause it contains ions (Recall Unit B: Chemistry)

An ____________ is a conductor through which electric currententers or leaves a device or material


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Electrochemical Cell

Is a package of chemicals designed to produce small amountsof electricity; electricity comes from chemical reactions

Two Types:DRY CELLS called dry because chemicals are in a________ and are sealed to prevent chemicals from leaking

Example: AA batteries

WET CELLS called wet because they use _________electrolytes, usually acids; generally cheaper and easier tomake

Example: Car battery


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Dry Cell

See pg. 288 Figure 1.20


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WetCell

The acidic electrolyte eats away thezinc electrode , leaving behindelectrons (leaving zinc ___________)

The acidic electrolyte leaves thecopper electrode alone but makes it_________________ charged

Electrons _______ along the wire from

the (-) zinc to the (+) copper electrode.The electric current will provide theenergy for a _________ (i.e. light)

Wet Cell


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Rechargeable Cells

The Dry and Wet cells we have studied so far are called:PRIMARY CELLS meaning they produce electricity fromchemical reactions that cannot be ______________

However, there are rechargeable cells called:SECONDARY CELLS meaning an external electricalsource (plug-in) can run electricity back though the cell andthis ___________ the original reactants. Then the cells can

be used over and over again (i.e. cell phone batteries)Will they wear out over time?? Yes but nickel oxide andcadmium batteries __________ efficiently so can berecharged hundreds of times


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Electrochemistry

The study of chemical reactions involving electricity

We will study the following:ElectrolysisElectroplatingAnodizingElectrorefining


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Electrolysis

The ________________ of a substanceby an electric current

Many industrial processes useelectrolysis to _____________ usefulelements

Examples:

Electrolysis of water produces the fuelfor the space shuttle____________ produced by electrolysisis used to make our drinking water safe


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Electroplating

Using electricity to _______ a thin layer of metal onto anobject

Examples:Jewelry Pure gold jewelry would bend and deform easily,so we use less expensive but ____________ metals andthen coat them a thin layer of gold


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The item to be coated and a bar of the coating metal areimmersed in an electrolyte, like electrodes in a wet cell

A source of ____________ is connected between the metals

The flow of electricity deposits atoms of the positivelycharged metal onto the negatively charged one

Used to protect metalsfrom _______________

How to Electroplate:


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AnodizingAnodizing - is a process to coat aluminum parts with alayer of _______________.The oxide coating is much harderthan pure aluminum.

Used in aluminum screen doors, airplane and car parts, etc.

Advantages of Aluminum Anodized Surfaces:Corrosion resistanceClean surfaceNon-conductive surface________________Color stabilityAesthetics


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ElectrorefiningElectrorefining removing ______________ from metal

Example: Impure gold is put into a strong acid with a thinstrip of pure gold. When current is applied, the dissolvedpure gold moves from the impure electrode, into theelectrolyte and then moves to the pure gold electrode where

it is deposited. The impurities are left _____________.
http://www.material.science.sudeshnapaul.com/Electrorefining.gifhttp://www.material.science.sudeshnapaul.com/Electrorefining.gif


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Electrical Safety Worksheet

Read pg. 284-287 to complete the Electrical Safetyworksheet

Assignment: pg. 294 #1-8

1.4 cells and batteries - student version

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